Suspension upgrade for 2011 convertible

[caljoe89]

New member here...

I've read lots about upgrading suspensions, but haven't seen much about convertibles and how certain set-ups differ on verts b/c of the weight. I just bought a used 2011 M sport vert and put new Michelin PSS's on them. I'm looking to upgrade the suspension and want to start with dampers/springs or coilovers. Being a vert, I doubt I'll ever track it, and this is my DD with regular rides with the wife, so comfort is key, but I do want something that will handle the twisty and very bumpy backroads around where I live.

I'm leaning towards Koni yellows with my stock (M sport) springs. I'm also interested in the ST coilovers. Bilsteins sounds too harsh riding, and Koni FSD's don't sound like they'll handle the bad, windy roads well since I do like to push it a little (without the wife of course).

Any experience out there with either the ST coilovers (or other sets) or the Koni yellows on verts? Any concerns about the added weight of the car on selecting suspension parts?

Any help would be appreciated as I love my car (especially with the PSS's), but really don't like the handling. Thanks in advance.

[128Convertibleguy]

If comfort is important to you, I'd go stock springs and FSDs. Check this out, a head to head comparison of stock BMW, FSD, and yellows on a 3 series. The first spider chart is eye opening.

http://www.tirerack.com/suspension/tests/koni_fsd.jsp

The yellows would no doubt handle better on a stiffer setting, but then the ride difference would be larger.

If you want to put on stiffer springs, the FSDs are wrong.

[SalemChiro]

I have a vert and I'm running Yellows with the stock sport springs, and PSS.
The ride is more compliant with the yellows over stock dampers. I have them set at 35% rebound damping from full soft. Talk to HP Autowerks if you have any questions about setup.

[caljoe89]

SalemChiro,

That's encouraging. Can I ask a few more questions? Do you have a 2011 or newer model with the linear sport springs vs the progressive? I don't know the difference but everyone is saying to use the newer springs with the koni yellows. Also, do you have the externally adjustable rear dampers or the regular ones that require you to remove then before adjusting? My understanding is that the externally adjustable ones are shorter bodies, so I don't know if that means anything in terms of needing to use shorter springs.

Thanks, this is very helpful!

[SalemChiro]

I'm using the stock 2008 springs with the "white body" external adjustable Koni Yellows. No fitment issues with these shocks.....and definitely worth the extra $$. One thing I would suggest, if you go with these shocks leave the trunk liner out for a few weeks so you have easy access to adjust the shocks to your preference. I started at 40% then went to 35% from full soft.

[gap]

Originally Posted by SalemChiro

I'm using the stock 2008 springs with the "white body" external adjustable Koni Yellows. No fitment issues with these shocks.....and definitely worth the extra $$. One thing I would suggest, if you go with these shocks leave the trunk liner out for a few weeks so you have easy access to adjust the shocks to your preference. I started at 40% then went to 35% from full soft.

Replaced the 6 year old PS front struts with the Koni yellows and it is a great improvement. The rear adjustable shocks are backordered. What rear upper shock mount did you use? Was looking for something firmer than stock but compatible with external adjustment. Dinan said theirs is not compatible with their external adjustable shock which I think is the same.

[SalemChiro]

Originally Posted by gap

Replaced the 6 year old PS front struts with the Koni yellows and it is a great improvement. The rear adjustable shocks are backordered. What rear upper shock mount did you use? Was looking for something firmer than stock but compatible with external adjustment. Dinan said theirs is not compatible with their external adjustable shock which I think is the same.

@gap: Regarding the rear upper shock mount. Are you referring to the bushing that has the nut attached to it that bolts in from the trunk?

If so, I lifted up the three tabs that hold the stock size nut in place...then swapped it with the correct size that comes with the shock.

[gap]

Originally Posted by SalemChiro

@gap: Regarding the rear upper shock mount. Are you referring to the bushing that has the nut attached to it that bolts in from the trunk?

If so, I lifted up the three tabs that hold the stock size nut in place...then swapped it with the correct size that comes with the shock.

I thought there was a separate upper shock mount but just found out it is part of the unibody. One less part to buy!

[djbrady]

Definitely interested in this thread as I have the EXACT same model. Just dumped the run flats for a set of AS3s and am now focusing on suspension. Definitely want to tighten things up and eliminate the awful bump-steer when I get on it around some twist and turns.

Any thoughts/comments on the Bilstein B12 setup? Seem to get a lot of positive reviews here.

[128Convertibleguy]

Originally Posted by djbrady

Definitely interested in this thread as I have the EXACT same model. Just dumped the run flats for a set of AS3s and am now focusing on suspension. Definitely want to tighten things up and eliminate the awful bump-steer when I get on it around some twist and turns.

Any thoughts/comments on the Bilstein B12 setup? Seem to get a lot of positive reviews here.

Bump steer? Two kinds. The classic is where the front toe changes over bunps, and steers the car. If you haven't modified the front suspension and it's in good condition, that kind of bump steer on a 1 series is unlikely. BMW designed the suspension to minimize it.

If it's the rear end stepping out over bumps, that's most likely the rear subframe bushings. Those soft bushings are a common 1 series problem. You can go a long way toward solving it with relatively inexpensive poly inserts, or pretty much eliminate it with M series bushings. Depending on your skill/comfort level with suspension work, those can be expensive.

DISCLAIMER - Just my amateur opinion. Your mods are your responsibility.

[caljoe89]

I'm thinking about doing the inserts at the same time as the dampers. Anything else to do to save on labor while I'm at it?

[caljoe89]

Ok. Ordered the externally adjustable Koni sports, and they're back ordered maybe a month. I'll have to search on how to remove the trunk liner in convertibles so I can adjust them but have seen a cool mod where someone cut holes so they don't have to remove the liner. I'm going to hold off on other upgrades so I can get used to each one first to tell what the difference is between mods. Now it's just a matter of waiting a month...

[pj.rodriguez]

Interested in your thoughts once you get them for you convertible. Subscribed

[caljoe89]

I was tired of waiting for the Koni's, so I cancelled the order and am getting the Bilsteins devlivered in a about a week. I'll post driving impressions after I get them installed which will have to wait until the new year. In the meantime, I've got some repairs to do, and I did get a PROCEDE tune, FMIC, and meth install, but that's for another post.

[caljoe89]

UPDATE: So I got the Bilstein HD's and took them in to get installed this week. The shop called me to today to say that they were having problems with alot of noise coming from the dampers. I talked to them again, and they said they contacted Bilstein and found out I had ordered the wrong parts. Bilstein told them that the part I ordered is for all trims of the 128/135 except those with M suspension, which my car has (M Sport trim).

I'm in contact with Tire Rack to see how I can return them, but since they're installed, their policy is not to except returns. I had ordered them off the website picking my make/model/year/trim selections and these show up as parts that will fit my car, so either 1) these are the wrong parts and the web site is incorrect, or 2) they are the correct parts and something is not being done correctly with the install.

I've given my VIN# to Tire Rack and they should get back to me tomorrow after doing some research. My mech is going to give me 1/2 of the reinstall, but I'm really unhappy since I've done lots of research and their own website confirms these should fit. I'll let folks know how it goes, but this is not fun. This is on top of the other issues I've had with the car including a leaking expansion tank and crankshaft sensor error code that came up after installing the PROCEDE tune and doing my own spark plug change.

[FactorX81]

I don't think the 135 has more than one suspension option. Msport sport and std are the same. If the dampers are the correct model for a 135 then its a bad part or install.

[caljoe89]

@ FactorX81, that's what I thought (except for the 1M), but I spoke to Bilstein today, and also got word back from Tire Rack. They both agreed that the B6 HD's are not the right part, and the B8 SP's are correct for my car. This is the first I've ever heard that, but they both confirmed that my car has a different suspension (M Sport trim, I forget what Bilstein called it and I don't know if it's the same as the 1M or not). To Tire Rack's credit, they are admitting their website is incorrect in selecting the B6's, and they are going to refund my money even though they've already been installed, and they are going to help cover some/all of the cost of reinstall which my shop will charge me 1/2 off to do. They shipped today and should arrive late next week. It's been quite an ordeal, but hopefully it'll all work out. The only thing left to fix then will be a crankshaft sensor error I got that may be related to my PROCEDE install I posted about in another thread.

[Clovef]

The 1m coupe has different rear shocks but not the M-sport suspension. The 135i suspension set ups are all the same other then a change to springs in 2011. I don't know about Bilstien parts fitment though.

[HP Autosport]

Originally Posted by caljoe89

New member here...

I've read lots about upgrading suspensions, but haven't seen much about convertibles and how certain set-ups differ on verts b/c of the weight. I just bought a used 2011 M sport vert and put new Michelin PSS's on them. I'm looking to upgrade the suspension and want to start with dampers/springs or coilovers. Being a vert, I doubt I'll ever track it, and this is my DD with regular rides with the wife, so comfort is key, but I do want something that will handle the twisty and very bumpy backroads around where I live.

I'm leaning towards Koni yellows with my stock (M sport) springs. I'm also interested in the ST coilovers. Bilsteins sounds too harsh riding, and Koni FSD's don't sound like they'll handle the bad, windy roads well since I do like to push it a little (without the wife of course).

Any experience out there with either the ST coilovers (or other sets) or the Koni yellows on verts? Any concerns about the added weight of the car on selecting suspension parts?

Any help would be appreciated as I love my car (especially with the PSS's), but really don't like the handling. Thanks in advance.

Koni Yellows with your M sport springs will likely have the same if not better performance than the ST coilers, minus the height adjustment, but you will have rebound damping adjustment.

With the increase weight of the vehicle we highly recommend the shorter body, custom valved Koni rear shocks for better control.


FSD's are okay, but may not offer you the performance improvement you are looking for.

[caljoe89]

So I finally got my car back with the Bilstein B8 (not B6) dampers installed with my stock sport springs. I'm very glad I didn't go with something softer like the FSD's. The rebound is much more controlled, but I don't have any of the harshness I was worried about with the stiffer Bilsteins. It's probably because I have the PSS's installed instead of the RFT's, so for me, they work great. That being said, I haven't driven it much on windy roads yet, but some hard turns and accelerations really show how loose the back end is, so much so that I get a little scared going WOT if it's not in a straight line. I'm sure the weight of the car doesn't help here, but I'm going to think hard about adding some of the other suspension mods folks have posted here.

So to conclude, B8's are much better than stock w/out any harshness, but from a handling POV I'm not really fully satisfied... maybe I never will be.

[WPG D33Z]

Originally Posted by Clovef

The 1m coupe has different rear shocks but not the M-sport suspension. The 135i suspension set ups are all the same other then a change to springs in 2011. I don't know about Bilstien parts fitment though.

Would Koni FSD pair up nice with the 2011 springs? Anything else that needs to be changed?